re: EnumAsteroid counts the rocks, and the hash join was mine to fix

EnumAsteroid is the frame record's FrameCount - 57/57, zero mismatches. Each
AsteroidFrameName is itself an IDXD record name; those records carry one named
field, FrameCount, plus a run of anonymous ones, and the anonymous fields
number exactly 8 x FrameCount on all 384 occurrences (ratio histogram
{8.0: 384}). The frame record is the placement table, 8 values per asteroid,
and EnumAsteroid counts the rocks. The frame-name -> EnumAsteroid map is
single-valued for all 64 names.

mission-wave-arrivals already met these records - they were the outliers that
broke its route-speed measurement, filtered out by name. regn-map-grid already
guessed the link and said so honestly ("a reading, not a measurement; nothing
here counts objects"). Neither says the count is exact.

The abandoned table lost its placement data too: exactly 7 of 64 frame names
have no record, and they are exactly the seven groups of the unreferenced
tenth object (Frame_Alpha_S01_Asteroid_{01,02,04}, Frame_Alpha_S01_Haze_
{01,02,03}, Frame_TAlpha_S01_Asteroid_03). 57 + 7 = 64, zero partials.

Withdrawing the previous commit's red flag: the hash join works and my call
was wrong. AsteroidDefinition values resolve to their objects' pak entry keys
as name_hash("stage\" + name), 9 of 9, each landing on the object the
frame-prefix join independently predicted. I had hashed the bare file name;
archive_naming.py hashes prefix + name over a path-prefix list. Two
independent joins, 9/9 agreement, both leaving the same tenth object
unreferenced.

Not settled: what the 8 values per asteroid are; why S28_p1 has a volume and
no definition.

All fifteen artefacts byte-identical.

docs/re/structures/asteroid-fields.md

@@ -73,14 +73,48 @@ the two sets share eight and differ by one each: **`S28_p1` has the collision
 volume for an asteroid field but no table saying which rocks to scatter in it**,
 while `test_s8p1` has a table with no volume of its own.
 
+## ✅ `EnumAsteroid` is the frame record's `FrameCount` — 57/57 (2026-08-28)
+
+Each `AsteroidFrameName` is itself an **IDXD record name**. Those records carry
+one named field, **`FrameCount`**, and a run of anonymous ones:
+
+* **`EnumAsteroid` equals that record's `FrameCount` in 57 of 57** frames that
+  have a record — **zero mismatches**, and the map is single-valued for all 64
+  frame names.
+* The anonymous fields number **exactly 8 × `FrameCount`, on all 384 occurrences**
+  (ratio histogram: `{8.0: 384}`). So the frame record is a table of
+  **8 values per asteroid** — the placement data — and `EnumAsteroid` counts the
+  rocks.
+
+[[mission-wave-arrivals]] already met these records: they were the outliers that
+broke its route-speed measurement, and it filtered them out by name, noting "the
+corpus already records that the 8-value frame is not universal". [[regn-map-grid]]
+already guessed the link — "a map's asteroids and debris, which the mission
+`Route` tables independently show as `Frame_S<NN>_Asteroid` records… stated as a
+reading, not a measurement; nothing here counts objects." **What neither says is
+that the count is exact.** Now it is measured.
+
+🔑 **The abandoned table lost its placement data too.** Exactly **7 of the 64**
+frame names have no record, and they are exactly the seven groups of the
+unreferenced object: `Frame_Alpha_S01_Asteroid_{01,02,04}`,
+`Frame_Alpha_S01_Haze_{01,02,03}`, `Frame_TAlpha_S01_Asteroid_03`. `57 + 7 = 64`,
+zero partials on either side.
+
+## ✅ The name→object join DOES reproduce by hash — with the path prefix
+
+Withdrawing the 🔴 from the first write-up. `AsteroidDefinition` values resolve
+to their objects' pak entry keys as **`name_hash("stage\" + name)`**, **9 of 9**,
+each landing on the object the frame-prefix join independently predicted. My
+first attempt hashed the bare file name; [[archive-naming]]'s resolver hashes
+`prefix + name` over a list of path prefixes, and `stage\` is the one that
+works here. (`Stage\` scores identically — the hash lower-cases.)
+
+**Two independent joins, 9/9 agreement**, and both leave the same tenth object
+unreferenced.
+
 ## 🟡 Not settled
 
-* What `EnumAsteroid` counts *of* — instances per frame is the obvious reading
-  and the 1…588 range fits, but it is untested.
-* Why `S28_p1` has a volume and no definition (S28 is the challenge mission that
-  alone flies `rou_f004`, see [[stage-numbering-and-player-craft]]).
-* 🔴 **The name→object join did not reproduce by hash.** `AsteroidDefinition`
-  values do not map to their objects' pak entry keys under `name_hash`, nor under
-  that key reduced `mod 0x00FFF9D7` or masked to 24 bits — the join above is by
-  frame prefix, which is direct. Either these keys are not name hashes or
-  [[archive-naming]]'s resolver differs from `unitgroup.name_hash`; not chased.
+* What the 8 values per asteroid are — position/rotation/scale is the obvious
+  reading, untested here; [[regn-map-grid]] has the neighbouring work.
+* Why `S28_p1` has an asteroid volume and no definition (S28 is the challenge
+  mission that alone flies `rou_f004`, see [[stage-numbering-and-player-craft]]).